The present invention relates to an integrated pressure management system that manages pressure and detects leaks in a fuel system. The present invention also relates to an integrated pressure management system that performs a leak diagnostic for the headspace in a fuel tank, a canister that collects volatile fuel vapors from the headspace, a purge valve, and all associated hoses.
In a conventional pressure management system for a vehicle, fuel vapor that escapes from a fuel tank is stored in a canister. If there is a leak in the fuel tank, canister or any other component of the vapor handling system, some fuel vapor could exit through the leak to escape into the atmosphere instead of being stored in the canister. Thus, it is desirable to detect leaks.
In such conventional pressure management systems, excess fuel vapor accumulates immediately after engine shutdown, thereby creating a positive pressure in the fuel vapor management system. Thus, it is desirable to vent, or xe2x80x9cblow-off,xe2x80x9d through the canister, this excess fuel vapor and to facilitate vacuum generation in the fuel vapor management system. Similarly, it is desirable to relieve positive pressure during tank refueling by allowing air to exit the tank at high flow rates. This is commonly referred to as onboard refueling vapor recovery (ORVR).
According to the present invention, a sensor or switch signals that a predetermined pressure exists. In particular, the sensor/switch signals that a predetermined vacuum exists. As it is used herein, xe2x80x9cpressurexe2x80x9d is measured relative to the ambient atmospheric pressure. Thus, positive pressure refers to pressure greater than the ambient atmospheric pressure and negative pressure, or xe2x80x9cvacuum,xe2x80x9d refers to pressure less than the ambient atmospheric pressure.
The present invention is achieved by providing an integrated pressure management apparatus for a vehicle having an internal combustion engine. The integrated pressure management apparatus comprises a housing defining an interior chamber, the housing including first and second ports communicating with the interior chamber; a pressure operable device separating the chamber into a first portion and a second portion, the first portion communicating with the first port, the second portion communicating with the second port, the pressure operable device permitting fluid communication between the first and second ports in a first configuration and preventing fluid communication between the first and second ports in a second configuration; a switch signaling displacement of the pressure operable device in response to negative pressure at a first pressure level in the first portion of the interior chamber; and a solenoid adapted for displacing the device from the first configuration to the second configuration during engine operation and thereby providing a performance diagnostic of the switch.
The present invention is also achieved by a volatile fuel vapor purge system for an internal combustion engine. The volatile fuel vapor purge system comprises a fuel tank having a headspace; an intake manifold in fluid communication with the headspace; a charcoal canister in fluid communication with the headspace; a purge valve having a first side in fluid communication with the intake manifold and having a second side in fluid communication with charcoal canister and with the headspace; and an integrated pressure management apparatus. The integrated pressure management apparatus includes a housing having an interior chamber in fluid communication with the charcoal canister; a pressure operable device separating the interior chamber into a first portion and a second portion, the first portion communicating with the charcoal canister, the second portion communicating with a vent port, the pressure operable device permitting fluid communication between the charcoal canister and the vent port in a first configuration and preventing fluid communication between the charcoal canister and the vent port in a second configuration; and a solenoid adapted for displacing the device from the first configuration to the second configuration during engine operation and thereby providing a performance diagnostic of the purge valve.
The present invention is further achieved by a method of providing a performance diagnostic of a purge valve connecting a charcoal canister to an intake manifold of an internal combustion engine. The method comprises providing an integrated pressure management apparatus; and actuating a solenoid of the integrated pressure management apparatus during engine operation to displace a pressure operable device of the integrated pressure management apparatus from a first configuration to a second configuration; and evaluating purge valve performance. The integrated pressure management system includes a housing having an interior chamber in fluid communication with the charcoal canister; the pressure operable device that separates the interior chamber into a first portion and a second portion, the first portion communicates with the charcoal canister, and the second portion communicates with a vent port. The pressure operable device permits fluid communication between the charcoal canister and the vent port in the first configuration and prevents fluid communication between the charcoal canister and the vent port in the second configuration; a switch signals displacement of the pressure operable device in response to negative pressure at a first pressure level in the charcoal canister; and the solenoid displaces the pressure operable device from the first configuration to the second configuration.